Does CO2 sink?

Question

OK: CO2 is denser than some other gaseous components of air. Does it 'pool' however - sinking in rooms, boxes, etc. to low levels?

I'm getting conflicting information on this one...

EDIT: for clarification, I am talking about atmospheric CO2, at 'normal' temperatures, say -10 degrees to +40 degrees, and CO2 expired by humans in a confined space, e.g. a room or box.

I'm still getting conflicting info! Can someone please back up their answers with facts? Dry ice, volcanic eruptions: all very interesting - but that doesn't fit with my scenario added above.
I understand CO2 is denser than O2, but I also note that the components of air do not seperate into layers in a room or a box. Or do they?

Answer 1

Yes. It's denser than air (which is roughly 80%nitrogen, 20% oxygen). Volcanigenic CO2 gas eruptions have been known; the gases silently and invisibly roll down the mountainside, suffocating all in its path (animals & humans), until the gas becomes sufficiently diluted with the air.

Answer 2

yes. CO2 has a molecular mass of 44g/mole while O2 has a molecular mass of 32g/mole and N2 is 28g/mole. This makes CO2 more dense and in the absence of convection currents to keep the gas particles mixed up, the CO2 will eventually settle to the bottom. The other gases would "float" on the CO2 layer.

However, the only realistic way this is likely to happen is if the CO2 is provided in the form of dry ice where the CO2 gasifies but is so cool and more dense than the other air that it sinks to the bottom almost immediately. If the CO2 is at the same temperature as N2 and O2, this isn't likely to happen in any normal room with any sort of circulation and would also depend on how much CO2 is present for it to be a concern.

Answer 3

Although CO2 in concentrated form will sink because it's denser than air, atmospheric CO2 will not sink any more than oxygen sinks to the bottom because it's denser than nitrogen. Components of a gas mixture spread out uniformly within rooms, boxes, etc. as if they were the only component in the mixture.

Answer 4

CO2 is denser than air so does go to the ground rather than the ceiling. It's easy to see this with Dry Ice.

Answer 5

Yes it does, being more dense than air. This is a very significant hazard when welding in enclosed places.

Answer 6

It seems to. Just look at the vapour from dry ice.

Answer 7

Oh yes.